UV artefacts when importing to Keyshot
Solution to this problem:
1.   
2.
Select all edges along top and bottom face of an engraved part and bevel those

*.
If you want to avoid strange reflections (on faces within the hole) when applying texture to blender model in keyshot, I recommend to bevel edges of a hole as well.
Model before beveling:

Model after beveling:

Hope this will help someone in the future. Thanks to HISEROD for the right direction.